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17803
June 8th, 2015 18:00
T7400- panel error # 1-3, power related problem
Dell T7400 3.0Ghz CPUx2, 750gb SATA x2. 16Gb (2gb x8)
The unit was started today, with the intention of testing some
SAS Drives. (the side panel is open) I installed a LSI 3080x
PCI-X SAS Controller, the bios saw the card and I was able to confirm
that 2 of the 4 drives I had tested ok. When I came back into the
room, I noticed a blank screen, thinking that I forgot to power on the
system in order to test the 3rd drive, I pressed the power button, and
the system did not power on, there was a low power on noise, and the
front panel displayed # 1-3, while the power button slowly flashed yellow
I downloaded some dell doc's, and determined that 1-3 are power related
problems, I followed the instructions, disconnecting each powered device
(video card, sata drives, and 2 dvd drives). there was no effect to the power
problem. I then removed the motherbrd power connection (power-1) and
the unit literally sounded like a normal boot, all fans spun up. I also
tested the power supply by pushing the small test button on the back
the LED came up green. Based on the information in the dell doc's
it would seem that the power supply is OK, but that the MB is the problem
The yellow LED on the Mb is on when the ac cord is inserted. There is no video
being displayed( tested 2 different cards) Would you agree that the MB is the problem
DELL-Shawn B
4 Apprentice
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540 Posts
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June 10th, 2015 11:00
Hi rjk24,
Thanks for the post and a great troubleshooting description! From what you’re describing I would certainly agree this sounds like a motherboard or power cable failure. It looks like you’ve already tried this but just to clarify, only the follow will need to be installed for POST, every other component can be disconnected to troubleshoot a power flow issue:
If you’ve already confirmed this, and the PSU is passing its BIST test, with the system reacting differently when you unplugged connection (power-1) I would suggest double checking that cable for any crimped points or socket damage before looking into a replacement for the motherboard and if available trading out the cable with a known good.
Regards,
speedstep
11 Legend
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47K Posts
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June 11th, 2015 08:00
The LED on the motherboard means 20W of +5VSB is available not that the power supply is ok.What happens when you remove all cables but power and press the BIST(Built in Self Test) button?
The LED on the back does not mean that the power supply is good.
The BIST (Built in Self test) is what that LED and button are for.
Power Supply Self Diagnostic Features
Some Dell computers have power supplies that include a self-diagnostic feature. The test button for the power supply is visible on the back of the system. This LED is not the same as the flea power LED on the motherboard (which also only says +5VSB is working NOT the Power supply is OK). Press and hold the self-diagnostic switch on the power supply -
* If the LED stays green, the supply is functioning
* If the LED stays off, get the power supply replaced